The present invention encompasses compositions and articles designed to bleach fabrics in an automatic dryer. More specifically, thickened chlorine bleaches releasably contained in a porous receptacle are distributed evenly over fabrics by the tumbling action of the automatic clothes dryer.
Compositions and processes designed to provide desirable functional and aesthetic benefits to fabrics are conventionally employed in a washing machine. Thus, fabric sizings, softening agents, bleaches, brighteners, and the like, are commonly formulated and provided as compositions designed for use either in an aqueous laundering liquor or in an aqueous rinse bath. More recently, the treatment of fabrics in automatic clothes dryers has been shown to be an effective means for imparting desirable properties thereto. For example, it is becoming common to soften fabrics in an automatic clothes dryer rather than during the rinse cycle of a laundering operation.
The most familiar method for bleaching fabrics to remove stains, especially in the context of a home laundering operation, is to add an oxidizing bleach directly to the laundering liquor. Liquid chlorine (as hypochlorite) solutions are usually employed, but solid chlorine bleaching compounds are also available. Such bleaches are designed for addition to the laundering bath in conjunction with the detergent, and provide the desired bleaching action concurrently with fabric laundering.
While through-the-wash bleaching processes are effective in most instances, they do suffer from several inherent drawbacks. The addition of either liquid or solid bleaches to the 10-25 gallons of water normally present in an automatic washing machine substantially dilutes the bleach, thereby reducing its effectiveness. For this reason, the quantities of bleach employed in a laundering bath are necessarily high to overcome the dilution effect. Moreover, certain stains can actually be "set" by oxidizing bleaches when used in combination with a detergent in an aqueous bath. For example, blood stains and mineral stains can be darkened by some oxidizing bleaches and become more tenaciously affixed to the fabrics. In such instances, it is more desirable to remove these kinds of stains by washing in the absence of bleach, and to complete the laundering operation by a later bleaching step. Additionally, many oxidizing bleaches contain ingredients which are not compatible with certain components of laundry detergents. Undesirable interactions can ensue when such bleaches and detergents are commingled in the laundering liquor.
The present invention relates to the use of chlorine bleaches, especially hypochlorite solutions, to bleach fabrics, preferably at elevated temperatures, e.g., in a clothes dryer. Chlorine bleaches offer distinct advantages over peroxygen bleaches, inasmuch as they are stronger and perform exceptionally well on heavily stained fabrics.
The concept of bleaching fabrics in a clothes dryer, rather than in an aqueous solution, has been disclosed heretofore. U.S. Pat. No. 3,701,202 describes a dispensing article for use in an automatic clothes dryer and suggests that fabrics may be softened, bleached and otherwise desirably treated in the dryer by means of such an article. See also U.S. Pat. No. 3,180,037.
U.S. Pat. No. 3,843,548, entitled COMPOSITIONS CONTAINING A SOURCE OF HYPOCHLORITE IONS, to R. James, issued Oct. 22, 1974, assigned to Wilkinson Sword, discloses clay-thickened hypochlorite bleaches, but does not disclose their use in the instant articles and processes. Peroxide bleaches thickened with silica gel are known in the hair bleaching art.
The co-pending application of Lucas, McKenna and Diehl, Ser. No. 437,570, filed Jan. 29, 1974, discloses bleaching articles.
The concurrently-filed applications of Bradley and Bradley, et al., Ser. Nos. 562,531 and 562,528, filed March 27, 1975 and March 27, 1975, respectively, relate to starch-thickened peroxygen bleaches and dispensing means therefor.
The concurrently filed application of Diehl, et al., Ser. No. 562,527, filed March 27, 1975, relates to thickened peroxygen bleaches and their use in dryers.
German Pat. No. 2,408,636, published Sept. 5, 1974, U.S. Application 335,311 Feb. 23, 1973, relates to the use of fabric treating agents other than bleaches encapsulated with various organic gelling agents and used, in solid form, in a clothes dryer.
Notwithstanding the potential advantage of bleaching fabrics in a clothes dryer, there are substantial problems with this mode of use. For example, it is essential that dryer-added bleaches be quickly and evenly dispersed over all surfaces of the damp fabrics being dried to insure that even and effective bleaching is obtained. Moreover, an optimal through-the-dryer bleach should not leave solid residues on fabrics.
It has now been found that solutions containing various chlorine bleaches can be thickened and conveniently used in a dryer. The thickened bleaches herein can be employed in porous pouches and are evenly and efficiently released therefrom by the tumbling action of the dryer. In a preferred mode, thickened aqueous solutions of chlorine (as hypochlorite) are used, thereby overcoming any problems with unsightly solid residues being left on the dried fabrics.
It is an object of this invention to provide compositions and articles especially adapted for use as through-the-dryer fabric bleaches.
It is another object herein to provide a means for evenly and efficiently dispensing bleaches onto fabrics in an automatic clothes dryer, or the like, without recourse to complicated dispensers or machine modifications.
These and other objects are obtained herein as will be seen from the following disclosure.